Wire-forming machine



Jan. 15, 1952 A, M. zwEYER WIRE-FORMING MACHINE 3 Sheets-Sheet l Filed April 22, 1946 Afro/eA/fns.

Jam w15, 1952 A. M. zwEYER l 2,582,576

WIRE-FORMING MACHINE Filed April 22, 1946 3 Sheets-Sheet 5 Arran/Ens.

Patented Jan. 15, 1952l l WIRE-FORMING MACHINE Andrew Max Zweyer, Los Angeles, Calif., alsignor, by mesne assignments, to Zig Zag Spring Co., a corporation of California` Application April 22., 1946, Serial No. 664,118

Claims.

This invention relates to wire-forming machines. and contemplates more specifically apparatus for imparting a tortuous contour to steel wire stock for subsequent tempering as a step in the manufacture of flat springs adapted particularly for use in cushion structures.

Springs of the type for the production of which the machine of the present invention is adapted are well known in the art. The wire stock of which such springs are composed is bent in the process of manufacture to form a series of uniform lateral offset curves or loops connected by straight, equi-spaced, usually parallel, reaches so as to delineate a symmetrical flat pattern with the loops lying in a common plane. In accordance with conventional utility of springs of this type, the ends thereof are equipped with brackets that are attached between suitable supports with the springs arcuately disposed in opposition to the load to be sustained. Variations in the weight or pressure applied to such a spring so arranged to receive the load from a direction extending in a plane through the terminals of the spring are resiliently compensated by the longitudinal expansion and contraction of the lateral offsets. Thus, a spring of this type is adapted to a'ord support for a cushion or the like over an area equal to its width and length with the entire load being absorbed between the ends and without any extension or contraction in the over-all length thereof.

However, the commercial manufacture of springs of this type involves numerous problems not encountered in the production of springs of any other form due to their essential tortuous contour. Heretofore in the art the only mechanism available for commercial manufacture of said springs was very complex, expensive, and relatively inflexible in its adaptation to manufacture of springs of different sizes.

It is accordingly a general object of the present invention to provide novel apparatus operable to form wire of the type above alluded to from steel spring wire stock fed continuously thereto so as to impart a flat, symmetrical winding contour to the wire. having substantially parallel reaches connected and equi-spaced apart by uniform loops adapted, when spring tempered, to resili-- ently sustain loads transversely applied.

More specifically. a principal object hereof is the provision of forming mechanism comprising a reciprocating table and an oscillator equipped with a pair of forming pins, the operation of the table andfoscillator being synchronized to bend the wire alternately around the respective pins to a variable extent depending upon the resiliency of the stock and the desired angle to be formed between the lateral offsets in the wire.

Another object is to provide an oscillator embodying self-feeding mechanism operable to draw stock from a source of continuous supply at a speed commensurate with the requirements of the forming apparatus, in combination with a composite roller drag to tension the stock and thereby assure uniformity in the results achieved by operation of the oscillator.

Another and highly important object is the provision of swinging arms alternately engageable with the wire as it is shaped by the forming mechanism to resist disturbance of the angular relationship between respective pre-formed lateral offsets in the wire incident to subsequent operations of the forming mechanism and further to insure the formation of straight reaches of wire between the loops therein by obviating any tendency of the wire to buckle or bow between the forming pins.

Another object is to provide a table and a roller superimposed thereon adapted to receive therebetween the wire as it leaves the forming mechanism to assure its continued movement toward a cutter or coiling apparatus, thereby preventing entanglement of the formed wire.

Numerous other objects and corresponding advantages of my invention, such for example as l simplicity of construction, continuous operation, ease of assembly, adjustment and replacement of worn parts, economy of manufacture and durability, Iwill be apparent to those of skill in the art to which my invention appertains from an examination of the following description read in the light of the accompanying drawings in which:

Fig. 1 is a plan view of a machine embodying my invention;

Fig. 2 is a plan view of the drive mechanism for the unit located below the principal support therefor, and, schematically, the gear and chain mechanism above the support by which the various forming apparatus is directly actuated;

Fig. 3 is a side elevation of the assembly.

Fig. 4 is a sectional view taken on lines 4 4 of Figs. 1 and 3;

Figs. 5 to 9 inclusive are diagrammatic views illustrating the successive steps, consecutively followed, during one-half cycle of operation of the oscillator and staying arms in the formation of a single lateral oilset in the wire stock from which the spring is constructed.

Referring to the drawings in detail, the numerals of which indicate similar parts throughout the several views, l0 designates generally a bench having a circular top Il supported by legs ally of motor I3 a shaft I1 is journalled in av bearing I8 suspended from the underside -of top I I for the rotatable support of a larger pulley I9 connected to pulley I by a belt 20. A smaller pulley 2l on the same shaft I1 is similarly connected to the larger pulley 22 carried by a shaft 23 journalled in a bearing 24 depending eccentrically from the underside of the circular table top II. The shaft 23 projects upwardly through the table top and through a housing 25.

On the upper end of shaftA 23 a drive sprocket 26 is mounted for engagement by a chain 21 adapted to transmit the motion of shaft 23 to a second sprocket 28, identical to sprocket 28, carried on the upper end of a` vertical shaft 29 suitably journalled in a bearing generally indicated at 38. Mounted upon and projecting upwardly from sprocket 28 is an eccentric crank pin 3l to which a connecting rod 32 is pivotally attached. The opposite end of rod 32 is pivoted to a bracket 33 secured rigidly to the side of a guide table 34 supported at one end on a pin 3 5 journalled in the table top II whereby rotation of sprocket 28 is adapted to impart oscillatory motion to the table 34 throughout the operation of the unit.

The wire stock 36 from which the spring is to be formed is supplied from a storage drum (not shown) suitably journalled laterally of the bench I0, and extends through a wire straightener, hereinafter described, and on to table 34 over the pivoted end of the latter. The wire is threaded through a double-roller guide 31 super- I imposed upon table 34 at the pivoted end of the latter. Intermediate the end of the table 34 and disposed normally in alignment with the 1 tension drag and guide 31 is a second doubleroller guide 38 mounted rigidly upon table 34 so askto oscillate therewith in response to the i operation of the sprocket 28. The tension drag comprises a channeled block 39 supported on a post 40 above the bench at a level correspondl ing to that of the oscillating table 34. The upwardly projecting sides 4I of block 39 are disposed parallel with the wire stock 36 which exltends therebetween from the storage drum to the guide 31 of table 34. At the outer end of block 39 and equi-spaced between its sides, a vertical pin 42 is mounted having a hole therethrough for the projection of the wire. either side of the wire a roller bar 43 is arranged carrying a plurality of peripherally-grooved rollers 44 adapted to be urged into contact with opposite sides of the wire. The rollers 44 of one bar 43 are oiset along the wire with respect to 1 rollers 44 of the other bar 43, and both sets of rollersare moved against the wire by a plurality of screws 45 threaded through the corresponding sides of the channel block 39,. The inner ends of screws 45 are accommodated in holes (not shown) in the sides of bars 43 so as to resist longitudinal movement ofthe latter while effectively controlling variation in the pressure of rollers 44 upon the wire incident to threaded adjustment of screws 45.

The oscillating table 34 is formed with a trans- I the tension drag assembly and the oscillating Ony verse opening 46 intermediate its ends and adjacent and forward of guide 38 for the accommodation of an oscillator which comprises a circular block 41 rotatably `mounted by suitable means upon a post 48 carried by bench I0. Encircling the bottom of the oscillator block 41 is a sprocket 49 engaged by a drive chain 50, opposite reaches of which encompass a larger sprocket 5I carried by a shaft 52 journalled in a suitable standard 53 supported by the bench top II directly below the extension of the wire 36 between table 34. Rotary oscillatory motion is thus transmitted tothe oscillator block 41 through chain 58 and sprocket 49 from the drive sprocket 26 by means about to be described. A crank arm 54 is secured to the upper end of shaft 23, carrying a crank pin 55 to which a connecting rod 56 comprising a turnbuckle assembly isl pivotally attached. The opposite end of the turnb-uckle connecting rod assembly 56 is correspondingly pivoted to a crank pin 51 carried by a crank arm 58mounted upon the upper end of shaft 52 to which the larger sprocket 5I is secured.

It will be observed that due tothe diierences in the degree of eccentricity of the respective crank pins 55 and 51 associated with sprockets 26 and 5I, the latter sprocket is oscillated rotatably through a cycle of slightly less' than onefourth of a revolution with 'each revolution of the drive sprocket 26. correspondingly, the relative sizes of sprockets 5I and 49 are such as to assure approximately a complete revolution of the oscillator block 41 with each arcuate stroke of the crank arm 58 associated with sprocket 5I. The guide table 34 is adapted to shift laterally and return to its initial position with each revolution of the oscillator. With the crank pin 51 at one end of itsv range of movement, the connecting rod 32. pivoted to sprocket 28, is equi-distant the ends of its range of movement whereby the guide block 38 is positioned in alignment with the reach of wire stock 36 extending between the tension drag and the guide 31. A half revolution of the drive sprocket 26 transmits through chain 21 a like degree of motion to the sprocket 28 which is eilective, first, to shift the guide 38 to an extreme lateral offset position in oneV direction and then return the sime to an intermediate position in alignment with the direction of movement of the wire stock 36 as it is drawn from the storage drum. On the second half revolution of the drive sprocket 26 the direction of movement of sprocket 5I is reversed, correspondingly reversing the motion of the sprocket 49 and oscillator block 41 which returns a full revolution to its original position. During this operation the crank pin 3| moves through the opposite half of its complete cycle so as to first shift the oscillating table 34 to the opposite side of its normal position from that to which it was moved during the rst half revolution of the drive sprocket 26, and then return the table to its initial position.

Mounted at diametrically opposite sides of the top of oscillator block 41 are a pair of forming pins 59 and 60 which project upwardly through the opening 46 in table 34 into the horizontal ateatro bent around the outside of one of the pins 59 and extends diagonally between the pins to the opposite side of the other pin 60 around which it is wound and then bent in a straight reach 6I across the forward arcs of the pins.

Superimposed above the oscillating table 34 is a beam 62 supported at one end by a suitable standard 63 mounted upon the top II of bench I laterally of table 34. Depending rotatably from bearing housing 64 carried by the beam 62, is a pair of shafts 65 located at opposite sides and just out of the range of movement of the table 34. The lower end of each shaft 65 carries a sprocket 66 disposed in a plane below table 34 and in horizontal alignment with chain 50 with opposite reaches of which each sprocket 66 is operatively engaged. I'he sprockets 66 are identical in size and number of teeth to provide for their reciprocatory movement through slightly more than 180 with each full revolution of the oscillator block 41. A staying arm 61 is secured rigidly to and projects radially from each shaft 65 in a horizontal plane above the forming pins 59 and 60, carried by the oscillator block 41. In-

termediate each arm 61 one end of a finger 68 is 1 pivotally connected so as to overhang the outer end of the arm, which is cut away to accommodate a wire-engaging pin 69 depending from the end of the finger. Pin 69 projects downwardly into the horizontal plane of the wire, in contact with reach 6I to which it is moved upon alternate strokes of its arm 61. It will be understood that during actuation of the sprocket I and chain 50. the sprockets 66 are rotated simultaneously in the same direction, but as arms 61 project later- -ally for movement throughopposed arcs, the pins 69 are swung in opposite directions so as to alternately shift the arms toward and away from the oscillator and the wire engaged with forming pins 59 and 60. The pressure exerted by the respective pins 69 of the staying arms 61 upon the wire coincident with the successive formation of the lateral offsets in the wire depends primarily upon the predetermined fixed relationship between the shafts 65 and arms 61. However, in order to permit critical variation of this factor upon which depends the angle formed between successive lateral reaches of the completed spring, as is hereinafter more in detail described, I provide an adjusting screw 10 threaded through the reduced outer end of each arm 61 to bear against the pin 69 depending from the outer end of the adjacent finger 68. By varying the extension of thel screw 10 in each arm 61, the angle between the finger 68 thereof and arm may be altered so as to in crease or decrease the extent to which the pin 69 overhangs the oscillator block 41 at the end of the forward movement of the arm. A retainer bar 1I, secured by suitable means to the top of each arm 61, overhangs the adjacent finger 68 to frictionally engage the latter after proper adjustment of screw 10 is determined to resist pivotal displacement of the finger on the returned stroke of the arm. After passing through the oscillator, the formed wire is moved toward the outer end of table 34 where a channeled track 12 is provided to direct the wire from the assembly to a suitable spool or cutter (not shown). The channel 12 is supported at the level of table 34 by a bracket 13 mounted upon the bench top Il and is spaced slightly from the outer end of table 34 so as not to interfere with the reciprocable movement of the latter. In order to assure the movement of the formed wire onto the channel 12, a roller 14 journalled between arms 15 pivoted to the opposite sides of the adjacent end of channel 12 bears upon*` the work as it leaves the oscillator. A helical spring 19, connected between "each arm 15 and the bench top I I therebelow, normally exerts sufficient tension upon the roller assembly to assure the performance of its intended function while permitting the roller` to be manually raised' incident to pivoting of arms 15 so as to expedite the initial placement of the wire thereunder. o

The operation of my invention is briefly described as follows: The wire is initially threaded through the hole in pin 42 between the sets of tension rollers 44 and between the rollers of the guides 31 and 38, and thence around the forming pins 59 and 60 of the oscillator and across the latter behind-the pin 69 of the adjacent staying arm 61 with the end projecting onto the forward end of table 34 under the roller 14. The tension drag is then adjusted by manipulation of screws 45 to restrain, to the desired extent, the free movement of the stock therebetween. As the bars 43 to which the rollers 44 are journalled are movable laterally independent of one another and may be also tilted relative to the wire extending therebetween, it will be appreciated that the pressure imposed by any of. rollers 44 upon the wire may not only be varied but also that the joint lateral movement of both bars 43 enables the critical alignment of the stock at the point of its extension from the tension drag with the guide 31.

Energization of motor I3 thereupon turns the drive sprocket 26 actuating the oscillator through the sprockets 5I and 49 and chain 50. Coincidently. rotation of sprocket 28 and the oscillation of the table 34 is initiated. Reference is now made to Figs. 5 to 9 inclusive, wherein the forming^operation is diagrammatically illustrated. Fig. 5 represents the more pertinent parts of the forming mechanism as shown in Fig. 1 in the position assumed at the conclusion of forming a lateral offset in the wire. It will be observed that the forming pin 59 is in a position maintaining the stock extending through the guide 38 in a taut condition and that the other forming pin 60 has just completed the formation of an oifset loop in the wire. The`pin 69 of the arm 61 is engaged with thetransverse reach 6I of wire, leaving pin 60 so as to resist any tendency of this reach of wire to alleviate the distortion being effected by the forming pins. The initial movement of the drive sprocket 26 from this illustrated relationship of the parts (in a clockwise direction as seen in Fig. 1) begins the counterclockwise rotation of the oscillator. The pin 69, of arm 61 is immediately shifted out of contact with the wire, and coincidently tension upon the wire by pin 69 is relieved.

Pin 60, moving forwardly with a quarter turn of the oscillator toward its position as seen in Fig. 6, bears against the reach 6I of the wire heretofore engaged by the pin 69 of arm 61 so as to draw additional stock through guide 38. During this operation of` the oscillator, the lateral movement of table 34 in the direction toward which the forming pin 59 is moved is begun, and coincidently the other arm 61 begins its movement from its retracted position. These movements of the arms and table 34 are continued through the following quarter turn of the oscillator block, during which operation pin 60 moves out of engagement with the wire reach 6|, and the pin 59 moves into contact with the back of the next lateral offset theretofore producedby pin 60. During the next quarter turn of the oscillator block 41, the pin 59 bears against the reach 11 of the wire 36 drawing additional stock through the guides 31 and 38 and contacts the wire at a rearward point. It will be noted from an examination of Fig. that pin 59, being laterally disposed with respect to the line of supply of the wire stock 36, produces a bend in the wire at the mouth of guide 38. A feature of the in-` vention resides in the proximity of the oscillator I1 to guide 38 whereby the distance between the bend in the wire, referred to, and the arc of movement of pin 60 is substantially equal to the distance to which the wire is moved in response to the urge of pin 59 during the third quarter of movement of the oscillator. This shifting of the wire brings the bend formed in a stock at the mouth of guide 38 into the arc of movement of pin 69. Thus, the coincident movement of the oscillator block 41 as above described, resulting in the contact of pin 60 against the bend in wire 36 as seen in Fig. 8, tends to increase the angle preformed in the stock at opposite sides of the bend. Attention is directed to the fact that as sprocket 28 will have traveled 90 by the time the oscillator reaches the position shown in Fig. 7,

table 34 will be moving toward its intermediate or central position at the moment the forming pin 60 contacts the wire stock (Fig. 8) so as to bend the wire around pin 60 more effectively. As

the oscillator moves through its final arc, i. e., from the position shown in Fig. 8 to that of Fig. 9, the forming pin 60 completes the oiTset as the guide 38 reaches its central position. During this operation the tendency of the forming pin 60 to shift laterally the formed wire in advance of the oscillator is compensated by the engagement of the pin 59 at the bend produced by pin 60 on the preceding operation soas to bend the reach rearwardly around the forward arc of pin 60.

During the ilnal movement of the oscillator in the direction depicted diagrammatically in Figs. 5 to 9, inclusive, the staying arm 61 reaches a forward position whereat the pin 69 contacts the second reach 6I of the wire to maintain the parallel relationship of the lateral sections of the wire previously formed and prevents any tendency of the wire section to bow or buckle.

As the wire stock employed in manufacturing springs of the type contemplated possesses a quality of resilience, it is necessary to overbend each offset in the forming operation to a greater extent than desired in the completed spring. It will be observed that this result is achieved at the end of each operation of the oscillator (see Figs. 5 or 9), the reach 11 being bent rearwardly 1 to an extent substantially equal to the diameter o'f pins 59 and 60, while the staying arms 61 alternately prevent disturbance of the angular rela- `tionship of the offset formed on the preceding operation.

As the staying arm moves out of contact with the latter reach of the wire, the resilience of the stock tends to partially straighten the bend formed around the forming pin. By proper adjustment of the parts which must be determined in accordance with the resilience of the wire stock employed, each lateral reach assumes a parallel relationship with those previously formed and extends at right angles to `the longitudinal axis of the spring, as illustrated. 1While the oscillator, as its operation is above described, makes a full revolution in eachdirection, the resilience of the work may necessitate either a greater or lesser degree of movement in order to produce a spring of the form depicted.

It will be appreciated that variation in the degree of rotation of the oscillator will also alter the contour of the springs produced'from stock of the same size and quality, e. g., by reducing the movement of the oscillator, a more loose winding in the completed article is eilected. The extent of this movement of the oscillator is controlled by adjustment ofthe turnbuckle connecting rod 56 in a conventional manner which, as will be obvious, increases or decreases the throw of the crank. Where adjustment of the turnbuckle is made in order to vary the angle between the adjoining offset reaches of the formed spring, corresponding adjustment of the screws 10 is required so as to assure the maintenance of the angle of each lateral offset during the forma-tion of the next succeeding offset.

While I have shown and described but one embodiment of my invention, it will be apparent to those of skill in the art to which my invention appertains that numerous changes in size, design, shape and number of the various parts may be 'made, without departing from the spirit of my invention as dened in the appended claims.

What I claim and desire to secure by Letters Patent is:

l. In wire-forming apparatus of the character described, a rotatable oscillator, a pair of forming pins carried by said oscillator equi-spaced from opposite sides of the axis of said oscillator and movable arcuately with the latter, means to direct wire to be shaped into engagement with said forming pins, means to rotatably oscillate said oscillator shifting said pins to bend the wire over said pins alternately in opposite directions and thereby form a series of lateral offsets in the wire, and staying elements alternately engageable with successive lateral offsets respectively in the wire during the formation of succeeding offsets.

2. In wire-forming apparatus of the character described, a support, an oscillator block pivoted to said support, a pair of forming pins mounted upon said block eccentrically with respect to the point of pivoting of the latter, means to direct wire from a source of supply to said forming pins, means to oscillate said block to swing said pins alternately againstsaid stock at successive points along its length to form a -plurality of lateral offsets in said wire, and a pair of staying arm assemblies alternately engageable with the lateral offsets formed in the wire to resist deformation of the relationship between said offsets during the shaping of following reaches of the wire.

3. In a wire-forming apparatus of thecharacter described, a pivoted table, means carried by said table to guide wire stock thereover, an oscillator carrying a pair of forming pins projecting into the plane of said wire adjacent said table to alternately engage and bend said stock, means to actuate said oscillator, and means to shift said guide means and table in directions opposite to the directions of movement of said forming pins, respectively, while the latter are bending said wire.

4. In Wire-forming apparatus of the character described, a support, a wire straightening and tensioning device mounted on said support, a

plane of the reach of said wire extending out of said guides, said pins being disposed at diametrically opposite sides of, and equi-spaced from, the axis of said block, and means to turn said block with the wire stock engaged with the pins thereof and to coincidentally shift said table so as to swing one of said guides and one of said pins against the stock in one direction while swinging the other of said pins against the stock in the opposite direction.

5. In wire-forming apparatus of the character described, a support, a wire straightening and tensioning device mounted on said support, a table pivoted on said support, a pair of guides carried by said table normally aligned with said wire straightening and tensioning devicey to receive and direct wire stock passing through the latter, a fonning block rotatably mounted on said support adjacent said table carrying a pair of eccentric forming pins projecting into the plane of the reach of said wire extending out of said guides, said pins being disposed at diametricallir opposite sides of, and equi-spaced from, the axis of said block, means to turn said block with the wire stock engaged with the pins 'thereof and to coincidentally shift said table so as to swing one of said guides and one of said pins against the stock in one direction while swinging the other of said pins against the stock in the opposite direction, and an arm pivoted to said support to engage said stock during and incident to the operation of said forming block and table to resist deformation of wire extending from the block at the opposite side of the latter from said guides.

6. In a wire-forming apparatus of the character described, a block having a pair of pins projecting therefrom in kparallel .relationship with the axis of the block, means to direct wire stock to be formed over said block between said pins, means to turn said block upon its axis, shifting one of said pins into engagement with one reach of the wire stock to advance said stock a predetermined distance over said block and move the other of said pins into engagement with a different reach of said stock to bend the latter around the first-mentioned pin.

7. In a wire-forming apparatus of the character described, a block having a pair of pins projecting therefrom in parallel relationship with the axis of the block, means to direct wire stock to be formed over said block between said pins, means to turn said block upon its-axis, shifting one of said pins into engagement with one reach of the wire stock to advance said stock a predetermined distance over said block and move the other of said pins into engagement with a different reach of said stock to bend the latter around the first-mentioned pin, and means to reverse the direction of said movement of said block to disengage said pins from the respective reaches of the stock last engaged.

8. A wire-forming machine comprising an oscillator having a pair of spaced' bending pins thereon, means for rotatably oscillating the oscillator about an axis between the bending pins through approximately 360, means for feeding wire to be bent toward the oscillator so as to be engaged by the bending pins and bent thereby laterally into zigzag form, and restraining arms mounted for oscillatory movement about axes parallel to the axis of oscillation of the oscillator and positioned laterally of the path of movement of the wire. each arm carrying a. restraining pin swingable toward the axis of oscillation of the f 10 oscillator to engage a portion of laterally bent wire-behind the bending pins and extending between the bending pins, and means for oscillating said restraining arms alternately in timed relation to the oscillator.

9. A wire-forming machine comprising an oscillator having a pair of spaced bending pins thereon and oscillatable about an axis between the pins, means for feeding Wire to be bent toward the oscillator. means for oscillating the 0scillator through approximately 360 with each oscillation terminating in a position wherein the `pins are on opposite sides of the direction of movement of the wire, the wire feeding means including means in advance of the oscillator oscillatable across the direction of movement of the wire for swinging the wire laterally, means for oscillating the last-mentioned means in timed relation to the oscillator, restraining arms pivotally supported for oscillatory movement about axes laterally with respect to the said means and oscillator, said restraining arms carrying restraining pins engageable with that portion of bent wire that is immediately behind both bending pins on the oscillator at the end of an oscillation, and means for oscillating the restraining arms alternately and in timed relation to the oscillator. f

10. A wire-forming machine comprising an oscillator havinga pair of spaced bending pins thereon and oscillatable about an axisv between the pins, means for feeding wire to be bent toward the oscillator, means for oscillating the oscillator through approximately 360 with each oscillation terminating in a position wherein the pins are on opposite sides of the direction of movement of the wire, the wire feeding means including means in advance of the oscillator oscillatable across the direction of movement of the wire for swinging the wire laterally, means for oscillating the last-mentioned means in timed relation to the oscillator in sympathy with the direction of oscillation of the oscillator durinar part of each oscillation but in opposition thereto during the remainder of each oscillation, restraining arms pivotally supported for oscillatory movement about axes laterally with respect to the said means and oscillator, said restraining arms carryingl restraining pins engageable with that portion of bent wire that is immediately behind both bending pins on the oscillator at the end of an oscillation, and means for oscillat-l ing gie restraining arms alternately and in timed rela on to the oscillator.

ANDREW MAX zwEYn/R.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 468,301 Cooper Feb. 2. 1892 566,379 Deck Aug. 25, 1896 905,130 Ayer Dec. 1. 1908 1,439,411 Griner Dec. 19, 1922 1,908,261 Koenig May 9. 1933 2,160,020 Horton May 30, 1939 2,331,294 Bank et al. Oct. 12, 1943 2.408.778 Huppert Oct. 8, 1946 FOREIGN PATENTS Number Country Date 272,428 Germany Mar. 31, 1914 

